Push arm and mounting structure for tiltable bulldozer blade



Aug. 21, 1962 R. w. LlCHTl 3,049,821

PUSH ARM MOUNTING STRUCTURE FOR TILTABLE BULLDOZER BLADE Filed Oct. 17, 1960 2 Sheets-Sheet 1 INV EN TOR.

ATTORNEYS 1962 R. w. LICHTI 3,049,821

PUSH ARM MOUNTING STRUCTURE FOR TILTABLE BULLDOZER BLADE Filed Oct. 17, 1960 2 Sheets$heet 2 INVENTOR. EobeTf [Al L/chf/ Y ATTORNEJ'8 United States Patent Ofifice 3,049,821 Patented Aug. 21, 1962 3,649,821 PUH ARM AND MOUNTHNG STRUCTURE FOR TILTABLE BULLDDZER BLADE Robert W. Liehti, Joliet, TEL, assignor to Caterpillar Tractor Co, ieoria, lit, a corporation of alifornia Filed Get. 1'7", 196%, Ser. No. 63,117 3 Qlaims. (Ci. 37-144) This invention relates to bulldozers and particularly to means for mounting the blade of tiltable bulldozers to prevent damage which results from stresses set up when a blade is adjusted to its tilt position.

The application relates to the correction of difiiculties which are described in detail in a co-pending application of Robert W. Lichti for Diagonal Brace Mounting for Bulldozer Blades, Serial No. 21,501, filed April 11, 1960 and also further described in a co-pending application of Richard K. Liess, entitled Diagonal Brace Mounting for Tiltable Bulldozer Blade, Serial No. 63,116, filed October 17, 1969. As described in said co-pending applications the conventional tiltable bulldozer is subjected to excessive compressive stresses in its diagonal brace when it is moved to a tilt position which stresses are reacted by the push arms and impart thereto bending forces often of sufiicient magnitude to result in breakage of an arm and particularly when the blade is subjected to a sidewise impact or force.

It is the object of the present invention to provide improved diagonal bracing for a tiltable type bulldozer and improved means for mounting the bulldozer blade with respect to push arms and diagonal braces thereof. It is also an object of the present invention to provide a bulldozer through which the forces above referred to are materially reduced and many undesirable stresses are eliminated. Still further and more specific objects and advantages of the invention are made apparent in the following specification by reference to the accompanying drawings.

in the drawings:

FIG. 1 is a schematic plan view of a tractor with a bulldozer embodying the present invention;

FlG. 2 is a fragmentary perspective view showing the rear of the bulldozer blade and also illustrating the structure of the push arms and diagonal braces of the present invention;

FIG. 3 is an enlarged fragmentary detail which shows a connection between the ends of the diagonal braces and the manner in which they are supported relative to the rear surface of the bulldozer blade;

FIG. 4 is a sectional view taken on the line IV-IV of FIG. 3; and

FIG. 5 is a schematic plan view of a tractor with a conventional bulldozer with forces imposed on the diagonal braces and push arms thereof indicated by arrows.

In FIG. 1 of the drawings, a tractor generally indicated at Ill is shown as provided with a bulldozer blade 31 carried at the forward ends of a pair of push arms 12.. At their rearward ends the push arms are connected in a conventional manner to the truck frames of the tractor as by ball and socket type joints shown at 13. The blade 11 is pivotally connected to the forward ends of the push arms as by universal or ball and socket joints shown at 15, and is held in an erect position by braces known as tilt braces which are broken away in FIG. 1 but are shown at 16 and 17 in FIG. 2. The tilt brace 17 includes adjustable means which may be in the form of a conventional extensible hydraulic cylinder 18. The tilt braces are connected as by pivot pins and brackets 19 to the tops of the push arms and ball and socket joints 20 to the back of the blade adjacent its upper edge. A pair of diagonal braces is usually employed and articulately connected between the inner sides of the push arms and the back of the blade 11 but in the present invention braces 22 and 23 are formed as integral parts of the push arms 12 and are articulately connected to each other at their inner ends as Well as to the rear surface of the bulldozer blade by means presently to be described. Push arms are conventionally made of steel plates welded together to form a box-like structure. The braces 22 and 23 are similarly formed in the present case to make them integral with the push arms. However, any method of construction may be used to provide a rigid connection between the arms and braces.

Conventional lift jacks such as shown at 26 in FIG. 1 are employed and extend between the tractor and bulldozer blade to the latter of which they are connected through brackets 27 fixed to the back of the blade. Other means may be employed for raising and lowering the blade, such for example, as cables actuated by winches on the tractor and the present invention is applicable to bulldozers where such other means are employed.

To effect tilting of the blade as for example toward the right, tilt brace 17 is lengthened by extension of the cylinder 18 fluid to which is supplied in the usual manner. Due to the bracing thus far described, this lengthening of the tilt brace 17 raises the left end of the blade as well as the forward end of the left push arm and imposes stresses on the diagonal braces and the push arm which are indicated by arrows in FIG. 5 of the drawings wherein conventional diagonal braces are shown at 22' and 23'. In FIG. 5, the left side of the blade has been raised and both diagonal braces are placed in compression as indicated by arrows a thus imposing a bending stress on each of the push arms which are shown at 12 in this figure. When this condition exists and the blade lit is subjected to a side thrust as indicated by the arrow the structure tends to collapse and a severe bending force is reacted by one of the push arms 12 at the point indicated by the arrow 0. This results from the addition of compression stresses to one of the diagonal braces while the stress on the other is relieved by the side thrust which imparts tension to the opposite diagonal brace as represented by the arrow d.

Through the present invention as through the invention described in the copending applications hereinabove referred to, the compressive stress in the diagonal braces and the bending stress on the push arms is reduced as well as distributed by reason of the integral connection of the diagonal braces with the push arms and the compressive stresses upon the diagonal braces are distributed between the two braces. This is accomplished as best shown in FIGS. 2, 3 and 4 through the integral connection of the diagonal braces with the push arms and by connecting the inner ends of these braces together in a manner'which permits slight twisting movement of one with respect to the other, slight movement of each toward the other and some movement between their connected ends and the back of the bulldozer blade 11. A universal and sliding joint is provided between the inner ends of the diagonal braces 22' and 23 which, as best shown in FIG. 3, is contained within a cap 30 secured as by cap screws 31 to the end of the diagonal brace 33. A hearing bushing of spherical contour shown at 32 is secured within the cap as by a tight press fit and receives a complementary hearing 33 with a spherical bearing surface thereon. This bearing is slidably fitted on a trunnion 34 carried by the end of the diagonal brace 22 thus connecting the ends of the braces 22 and 23 for sliding movement to and away from each other as well as for slight universal movement with respect to each other. A seal ring 35 is preferably employed between the end of the brace 22 and a bore in the end of the cap 30 to retain lubricant in the vicinity of this articulated connection and to exclude foreign matter therefrom.

Slight movement of the connected ends of the diagonal braces to and away from the bulldozer blade is permitted by a linkage illustrated in FIGS. 3 and 4 wherein brackets 36 are shown secured to the rear surface of the bulldozer blade 11 and pivotally supporting a link 37 by means of a pin 38. One of the diagonal braces, in this case the brace 23, is connected with a lower end of the link 37 by a pin 39 and a bracket 40 secured to the top surface of the brace. Through this connection, the ends of the braces are permitted to swing to and away from the blade and their swinging movement away from the blade is limited by an elongated slot in a link 41 which embraces the pin 39 and a pin 42 in a bracket 43 also secured to the rear surface of the blade.

With the arrangement above described, when the blade 11 is tilted by extension or retraction of the tilt cylinder 18, the inner ends of the braces 22 and 23 are permitted to move forwardly toward the rear face of the blade by means of the supporting linkage shown in FIG. 4 and are permitted to rotate slightly with respect to each other. This movement of the diagonal braces eliminates the undesirable bending stress normally applied to the push arms as illustrated in FIG. 5. When side thrust is applied to one end of the blade as indicated by the arrow b in FIG. 5, the inner end of one diagonal brace tends to move forwardly while the inner end of the other tends to move rearwardly. However, since the inner ends of the braces are connected together this tendency for them to move in opposite directions simply places a shear stress on the trunnion 34 thus resisting the side thrust and eliminating the bending stress normally imposed by tilting of the blade.

I claim:

1. In a tiltable bulldozer blade mounting which comprises push arms articulately secured to the blade, tilt braces extending upwardly between the push arms and the blade, a diagonal brace formed integrally with each push arm and extending inwardly therefrom and an articulate connection between the inner ends of said diagonal braces, said articulate connection comprising a ball and socket joint of which the socket portion is housed within an end of one of said diagonal braces and the ball portion is slidably supported on a trunnion fixed to the end of the other of said braces.

2. In a tiltable bulldozer blade mounting which comprises push arms articulately secured to the blade, tilt braces extending upwardly between the push arms and the blade, a diagonal brace formed integrally with each push arm and extending inwardly therefrom and an articulate connection between the inner ends of said diagonal braces, said articulate connection comprising a ball and socket joint of which the socket portion is housed within an end of one of said diagonal braces and the ball portion is slidably supported on a trunnion fixed to the end of the other of said braces, and a slidable sealing means between the ends of the braces to retain lubricant in the vicinity of said joint.

3. In a tiltable bulldozer blade mounting which comprises push arms articulately secured to the blade, tilt braces extending upwardly between the push arms and the blade, 21 diagonal brace formed integrally with each push arm and extending inwardly therefrom and an articulate connection between the inner ends of said diagonal braces, said articulate connection comprising a ball and socket joint of which the socket portion is housed within an end of one of said diagonal braces and the ball portion is slidably supported on a trunnion fixed to the end of the other of said braces, and means supporting the inner end of at least one of said diagonal braces to the bulldozer blade for limited movement to and away from the blade.

References Cited in the file of this patent UNITED STATES PATENTS 2,232,672 Low Feb. 18, 1941 2,764,824 Kepner Oct. 2, 1956 2,817,168 Mullin Dec. 24, 1957 2,942,363 Long June 28, 1960 

